Method and apparatus for membrane separation of air into nitrogen and oxygen elements for use in internal combustion engines

ABSTRACT

A method and apparatus for reducing the emissions and improving the performance of an internal combustion engine ( 40 ). An input air stream is separated into an oxygen-enriched air stream and a nitrogen-enriched air stream. The nitrogen-enriched air stream is received by a holding chamber ( 35 ). The oxygen-enriched air and a combustible fuel are provided to a combustion chamber ( 45 ) of the internal combustion engine ( 40 ) and a combustion process is initiated. After a predefined time delay, a volume of nitrogen-enriched air is provided from the holding chamber ( 35 ) to the combustion chamber ( 45 ) to be used during the rest of the combustion process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/502,472, filed Nov. 23, 2004, now U.S. Pat. No. 7,100,543 andcomprising the National Stage of International Patent Application No.PCT/US02/02168, filed Jan. 25, 2002, both of which being incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates to a method and system for reducing emissions andimproving performance of an internal combustion engine by providingoxygen-enriched air and nitrogen-enriched air to a combustion chamber.

2. Description of Related Art

The purpose of an internal combustion engine is to convert the chemicalenergy of fuel into the mechanical energy of motion using a process ofcombustion. As is known, internal combustion engines are usedextensively in a variety of machines including mobile vehicles, or forother purposes, such as power generation. However, internal combustionengines produce emissions from the combustion process which include anumber of pollutants whose presence are undesirable in the environment.As a result, numerous regulations have been implemented by variousgovernment bodies requiring reductions in these pollutants. The primarypollutants produced by internal combustion engines during the combustionprocess include oxides of nitrogen (NOx), carbon monoxide (CO),particulate matter (PM), and hydrocarbons (HC). Nitrogen oxides (NOx),such as nitric oxide and nitrogen dioxide, are formed during thecombustion process when air combines with oxygen under the hightemperature conditions of the engine's combustion chamber. Nitrogenoxides contribute to the formation of ozone, smog, and acid-rain. Carbonmonoxide is formed during the combustion process from the incompletecombustion of the air-fuel mixture. Carbon monoxide is a colorless,odorless, and toxic gas, and is one of the most dangerous of thecombustion process pollutants. Particulate matter is also formed duringincomplete combustion and consists of a mixture of solid and liquidmatter whose main constituent is carbon. Particulate matter is a majorsource of visible urban air pollution such as soot and haze.Hydrocarbons are formed from the combustible fuel and lubrication oilsand additives used within the engine. Both particulate matter andhydrocarbons are suspected carcinogens. In comparison to gasolineengines, diesel engines have particularly high concentrations ofnitrogen oxides and particulate matter contained in their emissions.

It has been known in the past that the introduction of oxygen-enrichedair into the combustion chamber during the combustion process allows formore complete combustion and results in a reduction in the formation ofparticulate matter, carbon monoxide, and hydrocarbons. An increase infuel efficiency, as well as engine power, can also be achieved throughoxygen-enrichment. However, oxygen-enrichment of the combustion processresults in an undesirable change in NOx production, as well as anincrease in combustion temperatures, which can cause engine overheating.An example of an oxygen-enrichment of intake air is described in U.S.Pat. No. 5,636,619. The method described in U.S. Pat. No. 5,636,619requires the use of a suitable NOx after-treatment device in the exhauststream to attempt to reduce the higher level of NOx generated by theoxygen-enrichment. However, U.S. Pat. No. 5,636,619 does not offer asolution to the problem of engine overheating caused byoxygen-enrichment of intake air.

The introduction of nitrogen-enriched air into the exhaust stream of aninternal combustion engine has also been known in the past to reduce NOxpresent in the exhaust gases. U.S. Pat. No. 5,640,845 describes a NOxreduction method which includes the injection of atomic nitrogen intothe exhaust gases of an internal combustion engine. However, U.S. Pat.No. 5,640,845 also does not offer a solution to the problem of engineoverheating caused by oxygen-enrichment of intake air.

The present invention provides for a reduction in emission pollutants,as well as increased fuel efficiency and engine power, while reducing oreliminating the disadvantages of prior methods. The introduction ofnitrogen-enriched air into the combustion chamber after the start ofcombustion provides for a reduction in the formation of NOx, whilereducing or eliminating the problem of engine overheating caused byoxygen-enrichment of intake air.

SUMMARY OF THE INVENTION

The present invention comprises a method and apparatus for reducing theemissions and improving the performance of an internal combustionengine. An input air stream is separated at least in part into anoxygen-enriched air stream and a nitrogen-enriched air stream. Thenitrogen-enriched air stream is received by a holding chamber. Theoxygen-enriched air and a combustible fuel are provided to a combustionchamber of the internal combustion engine and a combustion process isinitiated. After a predefined time delay, a volume of nitrogen-enrichedair is provided from the holding chamber to the combustion chamber to beused during the rest of the combustion process.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference ismade to the following detailed description taken in conjunction with theaccompanying drawings wherein:

FIG. 1 is a membrane 5 for the separation of air into nitrogen andoxygen elements in accordance with the principles of the presentinvention;

FIG. 2 is an apparatus 30 for the separation of air intonitrogen-enriched air streams and oxygen-enriched air streams for use inan internal combustion engine in accordance with the principles of thepresent invention; and

FIG. 3 is a method in flowchart form for the separation of air intonitrogen-enriched air streams and oxygen-enriched air streams for use inan internal combustion engine in accordance with the principles of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to the Drawings wherein like reference charactersdenote like or similar parts throughout the various Figures. Referringnow to FIG. 1, a membrane 5 for the separation of air into nitrogen andoxygen elements in accordance with the principles of the presentinvention is illustrated. The membrane 5 functions to separate airdirected into the membrane 5 into oxygen-enriched air streams andnitrogen-enriched air streams. The membrane 5 contains an inner membranematerial 10, which through a process of selective permeation orsolution-diffusion separates the air directed through the membranematerial 10 into an oxygen-enriched air stream and a nitrogen-enrichedair stream. This process can be accomplished due to the fact that oxygenhas a higher solubility through the inner membrane material 10 than thatof nitrogen. Typically, the membrane material 10 is composed of a bundleof hollow polymer fibers which selectively allow oxygen molecules todiffuse through the membrane wall while allowing nitrogen molecules topass through the hollow fibers without being absorbed.

During operation, an air stream is directed into the membrane 5 throughan air input port 15. Oxygen-enriched air is extracted from the membrane5 through an oxygen-enriched air output port 20 at a negative pressurerelative to that of the air at the air input port 15. Nitrogen-enrichedair is extracted from the membrane S through a nitrogen-enriched airoutput port 25 at a high pressure relative to that of theoxygen-enriched air. The desired high pressure of the input air streamcan be achieved by compressing, by various methods, the air stream priorto providing the air stream to the air input port 15. The purity of thenitrogen-enhanced air stream can be adjusted according to the flow rate,pressure, and temperature of the air stream fed into the membrane 5.

Referring now to FIG. 2, an apparatus 30 for the separation of air intonitrogen-enriched air streams and oxygen-enriched air streams for use inan internal combustion engine in accordance with the principles of thepresent invention is illustrated. An input air stream is directed intothe air input port 15 of the membrane 5 which separates the air into anoxygen-enriched air stream which is output through an oxygen-enrichedair output port 20, and a nitrogen-enriched air stream which is outputthrough a nitrogen-enriched air output port 25. The oxygen-enriched airstream is at a negative pressure relative to the pressure of thenitrogen-enriched air stream. In an example embodiment of the presentinvention, the oxygen-enriched air stream is at a negative pressure of16 inches, and the nitrogen-enriched air stream is at a pressure of 75psi. The oxygen-enriched air from the oxygen-enriched air output port 20is directed into a combustion chamber 45 of an internal combustionengine 40, such as a diesel or gasoline engine, and thenitrogen-enriched air is directed from the nitrogen-enriched air outputport 25 into a holding chamber 35. In an embodiment of the presentinvention, a compressor or blower, such as a turbocharger orsupercharger, may be used to increase the pressure of the input airstream before it is directed into the air input port 15 in order toallow the membrane 5 to more efficiently separate the oxygen andnitrogen elements of the air. Although the present embodiment of theinvention is illustrated by the use of a membrane, it should beunderstood that other methods and devices for separating an air streaminto oxygen-enriched air streams and nitrogen-enriched air streams couldbe used.

After the introduction of the oxygen-enriched air into the combustionchamber 45, a combustion process using the oxygen-enriched air andcombustible fuel is initiated. The introduction of the oxygen-enrichedair into the combustion chamber 45 allows for more complete combustion,produces more engine power, and increases fuel efficiency. In addition,the amount of particulate matter, carbon dioxide, and hydrocarbonspresent in the engine emissions is significantly reduced.

After a predefined time delay following the start of the combustionprocess, a predefined volumetric mass of nitrogen-enriched air isreleased from the holding chamber 35 and directed into the combustionchamber 45 to be used in the remainder of the combustion process. In oneembodiment of the present invention, the time delay for the introductionof nitrogen-enriched air is four milliseconds and the predefinedvolumetric mass of nitrogen is equal to that which gives a volumetricmass in the combustion chamber 45 of ninety percent nitrogen and onepercent unknown composition. However, the predefined time delay andpredefined volumetric mass of nitrogen-enriched air may be chosen basedon a variety of factors including the burn rate of the fuel, the gascomposition in the combustion chamber, speed of the engine, etc. Inaddition, the predefined volumetric mass can be changed continuouslyaccording to the operating conditions of the engine 40. Becausecombustion is already in progress, the nitrogen mass does not converteasily to NOx. As a result, NOx emissions are greatly reduced. Thereduced emissions provided by the present invention eliminates the needfor a catalytic convertor. The introduction of nitrogen also providesfor the added benefit of cooling the combustion chamber 45, whichproduces more engine power per volume of fuel and prevents overheatingof the engine 40. Control of the release of the nitrogen-enriched airfrom the holding chamber 35 can be accomplished through a variety ofmeans including injection nozzles, electronic valves, mechanical valves,pumps, etc. After the combustion process is complete, the exhaustemissions are expelled from the combustion chamber 45 through an exhaustoutlet 50.

In accordance with an alternative embodiment of the present invention,the oxygen-enriched air and nitrogen-enriched air are provided fromseparate sources, such as storage tanks, without the use of a membraneto separate the oxygen and nitrogen elements from an input air stream.

Referring now to FIG. 3, a method for the separation of air intonitrogen-enriched air streams and oxygen-enriched air streams for use inan internal combustion engine in accordance with the principles of thepresent invention is illustrated in flowchart form. In step 55, an inputair stream is provided to an oxygen and nitrogen separation device. Instep 60, the input air stream is separated into an oxygen-enriched airstream and a nitrogen-enriched air stream. In step 65, theoxygen-enriched air stream and combustible fuel are provided to thecombustion chamber of an internal combustion engine. Next, in step 70,combustion is initiated using the oxygen-enriched air and fuel mixture.As previously described in reference to FIG. 2, the introduction of theoxygen-enriched air into the combustion chamber allows for more completecombustion, produces more engine power, and increases fuel efficiency,as well as reduces the amount of particulate matter, carbon dioxide; andhydrocarbons present in the engine emissions. In step 75, a volume ofthe nitrogen-enriched air is provided to the combustion chamber after apredetermined time delay to be used in the remainder of the combustionprocess, thereby reducing NOx emissions and cooling the combustionchamber. Finally, in step 80, the emissions are exhausted from thecombustion chamber. The method is repeated for each cycle of thecombustion process.

Experimental results have shown that emissions, such as NOx and carbonmonoxide, can be reduced by eighty-two percent using the principles ofthe present invention. For example, a diesel engine that typicallyexhausts 2900 pounds of particulate matter per year into the atmosphereis expected to be reduced by 2378 pounds per year by using theprinciples of the present invention.

Although a preferred embodiment of the method and apparatus of thepresent invention has been illustrated in the accompanying Drawings anddescribed in the foregoing Detailed Description, it is understood thatthe invention is not limited to the embodiment disclosed, but is capableof numerous rearrangements, modifications, and substitutions withoutdeparting from the spirit of the invention as set forth and defined bythe following claims.

1. Apparatus for the operation of an internal combustion enginecomprising: means for providing oxygen-enriched air and fuel to acombustion chamber; means for initiating combustion of theoxygen-enriched air and fuel in said combustion chamber; and means forproviding, separately from the oxygen-enriched air, a predefined volumeof nitrogen-enriched air to the combustion chamber following apredefined time delay for use of the nitrogen-enriched air during theremainder of combustion within said combustion chamber; wherein thepredefined time delay is based upon at least one of burn rate of thefuel, combustion chamber gas composition, and engine speed.
 2. Theapparatus of claim 1 further comprising: means for separating an inputair stream to produce the oxygen-enriched air and the nitrogen-enrichedair.
 3. The apparatus of claim 2, wherein the means for separating aninput air stream comprises a membrane.
 4. The apparatus of claim 3,further comprising: means for providing the input air stream to themembrane.
 5. The apparatus of claim 2, further comprising: means forcompressing the input air stream prior to separating the input airstream to produce the oxygen-enriched air and the nitrogen-enriched air.6. The apparatus of claim 1, further comprising: means for holding thepredefined volume of nitrogen-enriched air prior to providing thepredefined volume of nitrogen enriched air to the combustion chamber. 7.The apparatus of claim 6, further comprising: means for releasing thepredefined volume of nitrogen-enriched air from the means for holding tothe combustion chamber.
 8. The apparatus of claim 7, wherein the meansfor releasing the predefined volume of nitrogen-enriched air comprisesat least one of an injection nozzle, an electronic valve, a mechanicalvalve, and a pump.
 9. The apparatus of claim 1, wherein the predefinedtime delay comprises substantially four milliseconds.
 10. The apparatusof claim 1, wherein the predefined volume of nitrogen-enriched aircomprises substantially ninety-percent of the volumetric mass within thecombustion chamber.
 11. The apparatus of claim 1, wherein the internalcombustion engine comprises a diesel engine.
 12. The apparatus of claim1, wherein the internal combustion engine comprises a gasoline engine.13. A method for the operation of an internal combustion engine having acombustion chamber, the method comprising the steps of: providing meansfor separating an input air stream to produce oxygen-enriched air andnitrogen-enriched air; receiving an input air stream in said separatingmeans and producing oxygen-enriched air and nitrogen-enriched airtherefrom; receiving the nitrogen-enriched air from said separationmeans in a first chamber adapted for flow communication with saidcombustion chamber; receiving the oxygen-enriched air from saidseparation means within said combustion chamber in combination with acombustible fuel for combustion therein; and selectively dischargingsaid nitrogen-enriched air from said first chamber into said combustionchamber after a predefined time delay relative to initial combustiontherein for use of said nitrogen-enriched air during the remainder ofthe combustion, wherein the predefined time delay is based upon at leastone of burn rate of the combustible fuel, combustion chamber gascomposition, and engine speed.
 14. The method of claim 13, wherein themeans for separating an input air stream comprises a membrane.
 15. Themethod of claim 14, further comprising: providing means for compressingthe input air stream prior to separating the input air stream to producethe oxygen-enriched air and the nitrogen-enriched air.
 16. The method ofclaim 13, wherein the predefined time delay comprises substantially fourmilliseconds.
 17. The method of claim 13, wherein the volumetric mass ofnitrogen-enriched air discharged into the combustion chamber comprisessubstantially ninety-percent of the volumetric mass within thecombustion chamber.
 18. The method of claim 13, wherein the internalcombustion engine comprises a diesel engine.
 19. The method of claim 13,wherein the internal combustion engine comprises a gasoline engine. 20.The method of claim 13, further comprising: holding the predefinedvolume of nitrogen-enriched air within the first chamber prior toproviding the nitrogen-enriched air to the combustion chamber.
 21. Themethod of claim 13, further comprising: repeating the steps of themethod for each combustion cycle of the internal combustion engine. 22.A method for the separation of air into nitrogen-enriched andoxygen-enriched air streams and subsequent use in an internal combustionengine for improving the efficiency thereof in reducing the amount ofparticulate matter therefrom, the method comprising the steps of:exposing the input air stream to a membrane adapted for separating theinput air into an oxygen-enriched air stream and a nitrogen-enriched airstream and the segregation thereof; injecting the oxygen-enriched airstream into a combustion chamber with fuel; initiating combustion of theoxygen-enriched air and the fuel within said combustion chamber; andinjecting the nitrogen-enriched air stream into said combustion chambersubsequent to the initiation of combustion therein, wherein theinjecting of the nitrogen-enriched air stream into the combustionchamber is performed after a predefined time delay, said predefined timedelay is based upon at least one of burn rate of the fuel, combustionchamber gas composition, and engine speed.
 23. The method of claim 22,further comprising: compressing the input air stream prior to separatingthe input air stream into the oxygen-enriched air stream and thenitrogen-enriched air stream.
 24. The method of claim 22, wherein thepredefined time delay comprises substantially four milliseconds.
 25. Themethod of claim 22, wherein the volumetric mass of nitrogen-enriched airinjected into the combustion chamber comprises substantiallyninety-percent of the volumetric mass within the combustion chamber. 26.The method of claim 22, wherein the internal combustion engine comprisesa diesel engine.
 27. The method of claim 22, wherein the internalcombustion engine comprises a gasoline engine.
 28. The method of claim22, further comprising: holding the nitrogen-enriched air stream withina first chamber prior to injecting the nitrogen-enriched air stream intothe combustion chamber.
 29. The method of claim 22, further comprising:repeating the steps of the method for each combustion cycle of theinternal combustion engine.